Polyvinyl halide compositions



Patented Nov. 26, 1940 UNITED sTATss 2.222.928 ronvmvr. minimcomrosrnous Claude H. Alexander, Cuyahoga Falls, Ohio, as-

signor to The B. F. Goodrich Company, New York, N. Y., a corporation ofNew York No Drawing.

6 Claims.

Thisinvention relates to polyvinyl halides, and -has as its object toprovide polyvinyl halide compositions with improved dielectricproperties.

Polyvinyl halides in general and plasticized 6 gamma polyvinyl chloridesin particular are very desirable materials for electrical insulationbecause they are extraordinarily resistant to water, oils, and othersolvents, they can be easily applied to conductors by a number ofmethods, and 10 the mechanical properties of the compositions can bevaried over a wide range'by changing the proportion of the plasticizer.The preparation of these compositions is disclosed in detail in U. S.Patent No. 1,929,453 issued to Waldo L. Semon.

I have discovered that the dielectric properties i of polyvinyl halidesare greatly improved by the concurrent presence in the compositions ofsulfur-free compounds containing cationic lead, and

sulfur or sulfur compounds containing bivalent or tetravalent sulfur.The term cationic lead is used to mean lead which has combined withother elements as a cation.

A great variety of sulfur-free compounds containing cationic lead,including thevarious lead oxides, lead nitrate, lead chloride, leadacetate,

- tetraphenyl lead, tetraethyl lead, triethyl lead chloride, leadoleate, lead stearate, lead oxalate.

lead' silicate, etc., may be employed. The lead compounds mayadvantageously be used in. pro- 3 portions as low as .5% or less and ashigh as 10% or over based on the weight of the plasticized composition.Compounds containing lead combined only as an anion such as sodiumplumbate are without the scope of this invention. There are a very greatnumber of compounds through which the bior tetravalent sulfur may besupplied to the composition. The compound may be one such as leadsulfide in which the lead and sulfur are combined. A combination of free40 sulfur and any sulfur compound may be used. Suitable bivalent sulfurcompounds include not only metallic sulfides, but also organic sulfurcompounds such as thioalcohols, thioethers, thioesters, thioaldehydes,thioacids, thiocarbamates,

mercaptothiazoles, and thiuram' sulfides, particularly compounds whichare di- .or polysuifides. Although the bivalent sulfur compounds arepreferred" to those having four .valences. tetravalent compounds such asthe metallic sulfites, particularly lead sulfite, may be used.

Application May 17, 1939, Serial No. 274,227

(01. zen-3s) A most useful embodiment of my invention is the combinationof lead oxide or a lead salt such as lead silicate with a plasticizercontaining hior tetravalent sulfur, which combination obviates the.necessity of using any other plasticizer and 5 produces compositionshaving superior dielectric properties. The plasticizer may also containfree sulfur, especially the monoclinic form which is usually conceded tobe bivalent Suitable sulfurcontaining plasticizers include thethianthrenes 10 such as 2,6 dimethyl thianthrene and organic sulfldessuch as diamyl thiodiglycollate and the dibenzyl ether oithiodiglycol.One of the valuable classes of such plasticizers comprises thethioethers having .the structural formula Rr-S-R' 5 wherein R is ahydrocarbon group such as methyl,

ethyl, isopropyl, amyl vinyl, cyclohexyl, benzyl, phenyl, etc., and R isan aryl group such as phenyl, tolyl, xylyl, naphthyl, xe'nyl, etc.Examples of this class of plasticizers include amyl beta-naphthylsulfide, cyclohexyl beta-naphthyl. sulfide, ditolyl sulfide, ethylalpha-naphthyl sulfide, isopropyl paratolyl sulfide, phenyl orthotolylsulfide, etc.

Materials such as carbon black, zinc oxide, clay, g5 barytesfwood flour,and other pigments and fillers commonly used in the rubber and plasticsindustries may also be included in the polyvinyl halide compomtions.

As a specific embodiment of my invention, I will show how the dielectricproperties of polyvinyl chloride compositions may be improved by usinglead compounds in conjunction with 2,6 dimethyl thianthrene. I prepareda composition containing gamma polyvinyl chloride 56 parts by weight,2,6 dimethyl thianthrene 42 parts, and

precipitated lead silicate 2 parts, and homogenized the mixture on aheated mill. The values for the power factors of this composition atvarious temperatures are as follows: 40

Temperature deg. 0;- 80 40 to 70 A00 Power factor at 1,000 cyclespercent ll. 6 12. 6 10. 8 8. 6 2. 0 1. 6

It can be readily seen that the power factoris very small at hightemperatures. It is especially noteworthy that at 0., the power factoris 'still. decreasing, a condition which I have never soolbtainedwithout using the method or this invent on. I

prepared containing, gamma polyvinyl chloride 50.9 partsjby weight, 2,8dimethyl thianthrene 39.1 parts, litharge 5.0 parts, and carbon black5.0 parts. The excellent dielectric properties of the composition areshown by the followi g:

pcraturc .-deg.0 so 4c Tom Power factor at 1,000 cycles percent 10.6.12.3 12.3 4.8 2.2 1.8

The extremely low power factor at high temperatures allows thecompositions of my invention to be used as insulation in many placeswhere former polyvinyl halide. compositions could not profitably beemployed.

It is my intention to claim only compositions of which the basis issubstantially a polyvinyl halide plastic, which compositions may containsuitable proportions of such adjuvants as plasticizera'stabilizers,'pigments, fillers, and the like, as has already been pointedout above, but not compositions which are basically of a diflerentcharacter, and consist largely of other plastics. The polyvinyl halidemay be a halide other than the chicride, such as the bromide, and mayeven be a copolymer of a vinyl halide with minor proportions of otherpolymerizable compounds such as vinyl acetate, but the best results areat present secured with the pure gamma polymer of vinyl variation ofproportions used are within the spirit As another specific example, acompositionwas valent sulfur.

and scope of the invention as defined in the appended claims. i F

I claim:

'1.-A composition is substantially} polyvinylhalide plastic, said 6composition comprising a sulfur-free compound containing cationic lead,and'a member 'of the class consisting of sulfur, compoundscontainingbivalent sulfur, and compounds containing tetra- 2. Acomposition'of matter of which the basis is substantially a polyvinylchloride plastic, said composition comprising a sulfur-free compoundcontaining cationic lead, and a member of the class consisting ofsulfur, compounds containing 15 bivalent sulfur, and compoundscontaining tetravalent sulfur.

3. A composition o'f matter containing poly vinyl chloride as the soleplastic-ingredient, said composition comprising a sulfur-free compound20 containing cationic lead, and a member of the containing cationiclead and a plasticizer containing bivalent sulfur.

5. A composition of matter of which th basis is substantially apolyvinyl chloride plastic, said composition comprising a sulfur-freecompound containing cationic lead and a thioether plasticizer having thestructural formula R-S-R" wherein R is a hydrocarbon group and R is anaryl group. 6. A composition of matter of which the basis issubstantially a polyvinyl chloride plastic, said composition comprisinga sulfur-freecompound containing cationic lead and amyl beta-naphthyl osulfide.

or mas-n which the basis

